This invention relates to razor blade assembly, in the form of a complete razor or a shaving unit for a razor. By `shaving unit` is meant a blade assembly which can be mounted on or formed integrally with a handle or a razor frame to provide a complete razor. In particular the invention relates to a disposable razor, that is to say one that is intended to be disposed of by the user when he considers that the razor is no longer giving an adequate shave. More particularly, the invention relates to the provision, in such a blade assembly, of means movable to expose the cutting edge of the blade for shaving or to render it safe so that it cannot harm anyone handling the blade assembly.